('85 150, 318 engine, 2 bbl holley carb, torquefilte tranny)

When accelerating slowly, "tip-toeing" away from a stop, all is ok.

If I try to accelerate quicker, the engine stumbles/bogs/flat spots and dies. It'll crank right up again.

It felt just like a worn out accelerator pump in the carburator. Or so I thought.....

New accelerator pump installed, no change in the bogging.

A swap with a known good, no flat spot carb....no change.

I'm baffled.

What else could duplicate a worn out accelerator pump type of stumble?

 

try and check the float level. and see if the throttle shaft is worn, that will let air in. next is see if the base gasket has a leak. tip: when working on a chrysler V8 be sure and cover the opening in each head just below the carb, cover it with a shop rag. those holes love to eat carb parts.

 

Replaced the carburator with a known good one, plugged the vaccum line going to the EGR valve, new spark plugs, new fuel filter, new fuel pump....no change.

Until the engine reaches operating temperature, it runs strong. Once it warms up, this stumble appears, always at the same rpm (i estimate it to be around 850-900).

It's almost like a switch has been turned off and on. If you push down on the gas pedal the engine starts pulling again.

Could it be the coil cutting out after the under hood temperatures heat up??